Spell Batching in Classic

Since we first announced World of Warcraft Classic, we’ve seen questions about spell batching. While we never really eliminated spell batching in WoW, we did change how (and how often) we process batches of actions coming from players, so you’re less likely to notice that processing in today’s game. We’ve been working to ensure that in WoW Classic, the gameplay of activating spells and effects will not differ from the experience of playing original WoW.

It was relatively common in the original game to see a warrior Pummel a mage who simultaneously and successfully Polymorphed the warrior. The mage suffered Pummel damage but no spell-school lock, because the mage didn’t get interrupted. This could seem paradoxical, but it could happen because the Pummel and Polymorph were both in the same batch, and were both valid actions at the start of the batch. For the most part, things like that don’t happen in modern WoW, but they still can. We’ve made improvements to batch frequency, and the game is much more responsive than it used to be. Still, if you manage to get both a Pummel and a Polymorph into a tiny processing window in modern WoW, you’ll experience the same behavior as in original WoW.

As with many other areas of WoW Classic, authenticity is our primary concern. It used to be the norm that combat flow and PvP balance were defined and tuned in a game where spell messages were resolved less frequently. There was a single game loop that processed all messages sent and received every server tick. Nowadays, the game processes multiple loops for messages of differing priorities. Spell casts are high priority, and have been for a long time.

For WoW Classic, we’re moving spell casts to a low-priority loop that will cause them to be processed at the frequency that best fits how the game actually played in version 1.12. Two mages will be able to Polymorph each other somewhat reliably, resulting in two sheep nervously pacing around at range. Two warriors will be able to Charge one another, and the end result will be both warriors standing stunned in each other’s original location.

We think it’ll be fun to see those sorts of things happening again.